1. Saudi Aramco - 12.5 million barrels per day

Saudi Aramco is by far the biggest energy company in the world, generating more than $1 billion a day in revenues. This image depicts the Shaybah mega-project, sitting on more than 15 billion barrels of oil in the Rub al-Khali desert. Aramco's biggest field, Ghawar, can do 5 million bpd. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)